The present invention relates to automotive four-wheel drive systems and, more particularly, to an oil pump anti-wear plate for the repair of transfer cases utilized in four-wheel drive vehicles of various manufacturers.
Presently there are many types of four-wheel drive systems. For purposes of this application the term “four-wheel-drive system” will be understood to define an automotive drive system for providing power to all four wheels on a part-time basis (i.e. four-wheel-drive can be switched ON and OFF manually).
The transfer case assembly or so-called transfer case 100 (FIG. 1) in such a part-time, four-wheel-drive system functions to lock the front-axle driveshaft to the rear-axle driveshaft so that all four wheels are forced to turn at the same speed. In the four-wheel-drive operating mode the vehicle is provided with substantially increased torque at the wheels to handle steep terrain and low-traction situations.
Currently many original equipment manufacturers utilize NEW VENTURE GEAR series 136, 236, 246, 261 or 263 transfer cases (hereinafter “the subject transfer cases”) in their four-wheel drive vehicles. Such transfer cases are commercially available from New Venture Gear Manufacturing GmbH, Roitzsch, Germany. In the subject transfer cases 100 an oil pump 120 is typically installed within a magnesium housing 125 (FIG. 2) that is utilized for weight reduction. The transfer case 100 is attached to the aft end of the transmission. The output shaft of the transmission (not shown) engages a mating internal spline 130 within the oil pump 120, which generates hydraulic pressure to a clutch pack in the transfer case 100 to initiate four-wheel-drive operation.
In the construction of the subject transfer cases, internal pockets 140 are formed on the interior surface of the magnesium housing 125 (FIG. 2), which are designed to receive integral anti-rotation lugs 155 formed on the aluminum oil pump 120 to secure it in position. Because a small amount of movement of the oil pump 120 is necessary to keep the pump centered on the transmission output shaft, a concentrated area of surface-to-surface contact occurs as at 145 and results in mechanical fretting between the lugs 155 and the magnesium housing 125 eventually causing the lugs to wear through the softer magnesium housing and resulting in oil leakage from the transfer case 100.
Thus, the present oil pump anti-wear plate and method of use has been developed to resolve this problem and other shortcomings of the prior art.